Page 190 - My FlipBook

174 THE TREATMENT OF TEETH

smooth them, the use of the strip is generally a
subsequent or final proceeding. It is therefore
often advisable, after having burnished as accurately
as possible, to remove the matrix, anneal and re-
apply it, and make the final adaptation with amadou,
or balls of wet cotton-wool. The strips may then
be again used to compress and finally perfect the
margins. The burnisher should not again be used
unless absolutely necessary.
A platinum matrix can be annealed in a Bunsen
burner, or, better still, in a very hot electric furnace.
A gold matrix should be placed on the electric
annealer or on a sheet of mica or platinum over a
spirit-lamp. Great care should be taken in re-
applying an annealed gold matrix in approximal
cavities, for the gold is now so soft that it may be
crumpled up in passing it between the teeth, and
rendered useless. Many operators find pieces of
rubber, fixed in suitable handles or mandrils, of
great use in perfecting margins. Mr. Rippon makes
considerable use of the indiarubber corks that
are supplied with small bottles, and finds them con-
venient to use for this purpose without mounting
them in handles.
In some cases when the adaptation of the matrix
—especially in regard to the margins—is difficult
or uncertain, a thin mix of the inlay body may be